Trichloromethylketones have been known for nearly 100 years. Gautier (Ann. chim., (6) 14, 345 [1888]) first prepared 2',2',2'-trichloroacetophenone by acylation of benzene with trichloroacetylchloride in 1888. Although there have been attempts to improve the results of this reaction (Blitz, H., J. Prakt. Chem., (2) 142 193 [1935]; Kaluszyner, A. and Reuter, S., J. Am. Chem. Soc., 75, 5126 [1953]) they have met with little success. Alternative methods for preparing trichloromethylketones have been reported which have the advantage of improved yields such as Houben's (Ber., 59B, 2878 [1926]) nitrile reaction and more recently the oxidation of the corresponding secondary alcohols (Shono, T., Kise, N., Yamazaki, A., and Ohmizu, H., Tettrahedron Lett., 23, 1609 [1982]; Atkins, P. J., Gold, V., and Wassef, W. N., J. Chem. Soc., Chem. Commun., 283 [1983]). Although the latter methods show some improvement, the yields, in general, are less than 50%.
The present invention employs a much improved method for the preparation of trihalomethyl ketones from trihaloacetylchloride and an aromatic compound. This invention relates to novel trihaloacetyl compounds and more particularly to aryl bis(trihaloacetyl) derivatives having the formula: ##STR1## wherein B.sub.1 and B.sub.2 are independently selected from ##STR2## and which may be the same or different and wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are independently selected from the group consisting of hydrogen, chlorine, bromine, an alkyl or an alkoxy group having from 1 to 4 carbon atoms, a phenyl group or ##STR3## wherein R.sub.1 and R.sub.2 have the aforesaid meaning, X is chlorine or bromine and A is a single valence bond, oxygen, sulfur, ##STR4## an aromatic group having the formula ##STR5## X, R.sub.1, R.sub.2, R.sub.3 and R.sub.4 having the aforesaid meanings and wherein n is an integer from 1 to 6.
Although U.S. Pat. No. 3,150,187 claims aryl dihalogenacetyl derivatives as useful materials which inhibit the growth of Mycobacterium tuberculosis no mention is made of the trihalogenacetyl derivatives or of any use of them.
The present invention involves the reaction of an aromatic compound with a haloacetyl halide in the presence of a Friedel-Crafts catalyst.